Several authors have argued that contractualism faces a dilemma when it comes to justifying risks generated by socially valuable activities. At the heart of the matter is the question of whether contractualists should adopt an ex post or an ex ante perspective when assessing whether an action or policy is justifiable to each person. In this paper I argue for the modest conclusion that ex post contractualism is a live option notwithstanding recent criticisms raised by proponents of the ex ante perspective. I then consider how an ex post contractualist can best respond to the problem that it seems to prohibit a range of intuitively permissible and socially valuable activities.